Trench Crusade (stylized in all caps) is a miniature wargame and grimdark horror setting. The game uses 32 mm scale miniatures, and can be played using "whichever miniatures bring [the players'] vision to life."

The setting of Trench Crusade is an alternate history that diverges from real history in the late 11th century. After the First Crusade's successful capture of Jerusalem, members of the Knights Templar committed "the Act of Ultimate Heresy," opening a gateway to Hell. Jerusalem was destroyed and the forces of Hell soon conquered most of the Levant.

The game takes place in the year 1914, after more than 800 years of conflict. The forces of Hell have conquered one-third of humanity, including large areas of the Middle East, Anatolia, the Armenian highlands, the Caucasus, the Balkans and part of the Saharan Africa, as well as footholds in Northern Italy, Gibraltar, Cordoba, Avignon, and Finland. The armies are at a stalemate, with both sides now engaged in trench warfare. The area between the forces of Heaven and Hell are a no man's land, in which small warbands from both sides conduct missions to gather intelligence, find artifacts and relics, search for enemy scouts, assassinate high-value targets, and capture prisoners.

The setting features several factions on both sides of the war, most with optional variants. Factory Fortress, Inc. has also partnered with third-parties to create licensed variants.

Trench Crusade is typically played between two players. Each player fields a "warband" of around 6-20 miniature models. The goal is to score more Victory Points than the opposing player by completing scenario objectives and "Glorious Deeds". Alternatively, either warband may lose the game by failing a "Morale Check".

Play takes place on a battlefield, typically a 3-4 foot square table or a similar surface, filled with miniature terrain to act as cover, obstacles and elevation. Players set up the battlefield and deploy their models according to the chosen scenario, usually in zones on opposing sides of the battlefield.

Combat is played in game turns. At the beginning of each turn, the player with fewer models gains the Initiative, with ties being resolved by dice roll. The player with the Initiative influences the order in which events resolve during that turn, including which player activates a model first.

During each turn, players alternatively activate their models, allowing them to take Actions such as moving, dashing, shooting, fighting in melee, performing situational actions and using special abilities. Each Action may be performed once per activation. Many Actions require a "Success Roll" to complete, where the player rolls a number of six-sided dice and must roll a sum of at least 7 on two of the dice to succeed. Various circumstances add positive and negative dice to the roll, with net positive rolls using the highest two dice and net negative rolls using the lowest two dice for the result. Some Success Rolls are "Risky" and will end the model's activation if failed.